Machine tools having tool changers to replace one type of tool with another type or to replace a worn tool with a new tool are known in the art.
U.S. Pat. Nos. 3,073,024; 3,133,349 and 3,174,222 illustrate machine tools for metalworking wherein a tool changer enters the rear of a vertically oriented and movable tool spindle. The tool changer is movable by a fluid cylinder relative to the spindle to insert a tool into the rear of the spindle and also to withdraw the tool from the spindle through its rear end. The tool changer also is moved relative to a tool storage chain or carousel to exchange tools therewith.
U.S. Pat. No. 4,658,494 discloses apparatus for drilling printed circuit boards wherein a drill bit transfer device pushes a drill bit of desired size from a tool holding magazine and transfers the selected drill bit to a position where it is aligned with the chuck or collet of a drilling unit for gripping by same. The apparatus includes a drill bit tip sensing device that interrupts operation of the apparatus when the device detects that the tip is incorrectly positioned.